The agency says a pair of slashed profit forecasts from SNC-Lavalin in the past three weeks — which first halved the per-share earnings target and then cut it again by more than 40 per cent — will make for a higher debt ratio.

The downgrade to BBB- from BBB notes the Montreal-based company has halted all bidding on future mining projects following a dispute with Chile’s state-owned copper mining company Codelco, now entering arbitration.

Standard & Poor’s says SNC-Lavalin’s growth prospects for oil and gas have “deteriorated” as the diplomatic feud continues between Canada and Saudi Arabia.

The agency also highlighted the prospect of a ban of up to 10 years on contracts with the federal government in Canada.

The ban is one possible outcome that could flow from a conviction on fraud and corruption charges stemming from alleged dealings with the Libyan regime under Moammar Gadhafi between 2001 and 2011.

The downgrade came after the federal ethics commissioner launched an investigation into allegations the Prime Minister’s Office put pressure on former attorney general Jody Wilson-Raybould to help the company avoid a criminal prosecution. Prime Minister Justin Trudeau has denied directing Wilson-Raybould on the matter.